PSGI toolkit and server adapters
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    Plack - Perl Superglue for Web frameworks and Web Servers (PSGI toolkit)

    Plack is a set of tools for using the PSGI stack. It contains middleware
    components, a reference server and utilities for Web application
    frameworks. Plack is like Ruby's Rack or Python's Paste for WSGI.

    See PSGI for the PSGI specification and PSGI::FAQ to know what PSGI and
    Plack are and why we need them.

    Plack::Handler and its subclasses contains adapters for web servers. We
    have adapters for the built-in standalone web server HTTP::Server::PSGI,
    CGI, FCGI, Apache1, Apache2 and HTTP::Server::Simple included in the
    core Plack distribution.

    There are also many HTTP server implementations on CPAN that have Plack

    See Plack::Handler when writing your own adapters.

    Plack::Loader is a loader to load one Plack::Handler adapter and run a
    PSGI application code reference with it.

    Plack::Util contains a lot of utility functions for server implementors
    as well as middleware authors.

  .psgi files
    A PSGI application is a code reference but it's not easy to pass code
    reference via the command line or configuration files, so Plack uses a
    convention that you need a file named "app.psgi" or similar, which would
    be loaded (via perl's core function "do") to return the PSGI application
    code reference.

      # Hello.psgi
      my $app = sub {
          my $env = shift;
          # ...
          return [ $status, $headers, $body ];

    If you use a web framework, chances are that they provide a helper
    utility to automatically generate these ".psgi" files for you, such as:

      # MyApp.psgi
      use MyApp;
      my $app = sub { MyApp->run_psgi(@_) };

    It's important that the return value of ".psgi" file is the code
    reference. See "eg/dot-psgi" directory for more examples of ".psgi"

  plackup, Plack::Runner
    plackup is a command line launcher to run PSGI applications from command
    line using Plack::Loader to load PSGI backends. It can be used to run
    standalone servers and FastCGI daemon processes. Other server backends
    like Apache2 needs a separate configuration but ".psgi" application file
    can still be the same.

    If you want to write your own frontend that replaces, or adds
    functionalities to plackup, take a look at the Plack::Runner module.

    PSGI middleware is a PSGI application that wraps an existing PSGI
    application and plays both side of application and servers. From the
    servers the wrapped code reference still looks like and behaves exactly
    the same as PSGI applications.

    Plack::Middleware gives you an easy way to wrap PSGI applications with a
    clean API, and compatibility with Plack::Builder DSL.

    Plack::Builder gives you a DSL that you can enable Middleware in ".psgi"
    files to wrap existent PSGI applications.

  Plack::Request, Plack::Response
    Plack::Request gives you a nice wrapper API around PSGI $env hash to get
    headers, cookies and query parameters much like Apache::Request in

    Plack::Response does the same to construct the response array reference.

    Plack::Test is a unified interface to test your PSGI application using
    standard HTTP::Request and HTTP::Response pair with simple callbacks.

    Plack::Test::Suite is a test suite to test a new PSGI server backend.

  Patches and Bug Fixes
    Small patches and bug fixes can be either submitted via nopaste on IRC
    <irc://> or the github issue tracker
    <>. Forking on github
    <> is another good way if you intend to
    make larger fixes.

    See also <> when you think this
    document is terribly outdated.

  Module Namespaces
    Modules added to the Plack:: sub-namespaces should be reasonably generic
    components which are useful as building blocks and not just simply using

    Middleware authors are free to use the Plack::Middleware:: namespace for
    their middleware components. Middleware must be written in the pipeline
    style such that they can chained together with other middleware
    components. The Plack::Middleware:: modules in the core distribution are
    good examples of such modules. It is recommended that you inherit from
    Plack::Middleware for these types of modules.

    Not all middleware components are wrappers, but instead are more like
    endpoints in a middleware chain. These types of components should use
    the Plack::App:: namespace. Again, look in the core modules to see
    excellent examples of these (Plack::App::File, Plack::App::Directory,
    etc.). It is recommended that you inherit from Plack::Component for
    these types of modules.

    DO NOT USE Plack:: namespace to build a new web application or a
    framework. It's like naming your application under CGI:: namespace if
    it's supposed to run on CGI and that is a really bad choice and would
    confuse people badly.

    Tatsuhiko Miyagawa

    The following copyright notice applies to all the files provided in this
    distribution, including binary files, unless explicitly noted otherwise.

    Copyright 2009-2011 Tatsuhiko Miyagawa

    Yuval Kogman (nothingmuch)

    Tokuhiro Matsuno (tokuhirom)

    Kazuhiro Osawa (Yappo)

    Kazuho Oku

    Florian Ragwitz (rafl)

    Chia-liang Kao (clkao)

    Masahiro Honma (hiratara)

    Daisuke Murase (typester)

    John Beppu

    Matt S Trout (mst)

    Shawn M Moore (Sartak)

    Stevan Little

    Hans Dieter Pearcey (confound)

    Tomas Doran (t0m)


    Mark Stosberg

    Aaron Trevena

    The PSGI specification upon which Plack is based.


    The Plack wiki: <>

    The Plack FAQ: <>

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.